[PATCH] Kconfig fix (ppc 4xx and early serial)

a bunch of ppc 4xx variants unconditionally calls early_serial_setup() and
therefore needs SERIAL_8250

Signed-off-by: Al Viro <viro@parcelfarce.linux.theplanet.co.uk>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>